A substantial body of scientific evidence exists to support the proposition that a human subject may be influenced by visual messages generated at intensity and duration levels sufficiently low that they are not consciously perceived by the subject. U.S. Pat. Nos. 3,060,795 and 3,278,676 disclose a variety of systems adapted to display a supraliminally perceptible visual image having a subliminally perceptible message superimposed thereon. These patents disclose motion picture and television systems for displaying conventional programs along with secondary visual signals that have such low levels of intensity and/or duration that they are not consciously perceptible by a human observer but are capable of impressing themselves upon the subconscious mind of the observer to influence behavior.
The systems disclosed in these patents as well as the subsequent subliminal visual message system disclosed in U.S. Pat. No. 4,006,291 all involve arrangements wherein both the source of the supraliminal program signal and subliminal message signal are under control of the system's operator. In the motion picture version disclosed in U.S. Pat. No. 3,060,795, a pair of separate motion picture projectors employ mechanism connecting them so that they operate in synchronism to generate the supraliminal program signal and the superimposed subliminal mesasge. In the television versions disclosed in the above-noted patents, pairs of television cameras are used to generate the two signals and their outputs are synchronized to provide a combined signal suitable for use directly by a television receiver or for radio transmission to remote receivers.
The highly specialized apparatus required for these prior art systems has severely limited their application. If a subliminal mesasge system could be formed with readily available equipment, such as a home television receiver, which could use conventionally broadcast programs as the supraliminal program source, it would have great utility for impressing the observer with subliminal message that might educate the observer or direct him or her toward desirable action.